1. Technical Field of the Invention
The present invention relates to an apparatus for detecting division lines, which apparatus is able to detect division lines painted on a road surface, for example, to indicate roadsides, lane lines, park lanes, and the like, and to a method for detecting division lines.
2. Related Art
An apparatus has been known, with which division lines are detected to effect control, such as lane-keeping control, of the vehicle equipped with the apparatus.
For example, JP-A-2003-121546 discloses, as such an apparatus, an apparatus that uses a luminance difference between a lane marker (including a division line) and a road surface, which luminance difference is obtained from an image of a landscape picked up by a camera in the forward direction of the vehicle. This apparatus also recognizes a lane marker by performing pattern matching against display/arrangement patterns of lane markers prepared in advance. This patent document also discloses an apparatus that uses a laser radar in combination to identify the type of a lane marker, based on the reflection intensity of a laser beam (electromagnetic wave) and selects an optimum recognition method depending on the type of the lane marker identified.
Also, JP-A-2004-139338 suggests making use of a laser radar. This laser radar is installed in a vehicle to detect a distance and a relative speed, for example, between a preceding vehicle and the vehicle installing the laser radar. This patent document suggests using this laser radar for the detection of a division line.
The technique disclosed in JP-A-2003-121546 is able to detect the location of a division line based on the reflection intensity of a laser beam, however, is not able to accurately calculate the edges of the division line. Therefore, if this technique of detecting a division line is applied to a technique, such as of lane keeping control, that requires high safety, the detection accuracy is required to be improved.
Also, as disclosed in JP-A-2004-139338, use of two techniques, i.e. camera and laser, in combination enables calculation of the edges of a division line. However, this necessitates installing both of a camera and a laser and thus increases the size of the apparatus as a whole.